Apparatus for shielding process chamber port having dual zone and optical access features

ABSTRACT

A port in a window member provides first access to a process chamber interior for gas injection and second optical access for process analysis and measurement. Plasma-induced etching and deposition in a bore of a gas injector integral with the window member is reduced by a grounded shield surrounding an access region, and coatings reduce particle flaking from walls of a first clear optical aperture of the injector and from a second clear optical aperture of a gas and optical access fitting,. The shield surrounds the region, and is configured with couplers to hold the gas and optical access fitting to the window member for access to the injector. The couplers compress seals so that a gas bore in the fitting is sealed to a plenum of the injector, while allowing optical access into the chamber through the first clear optical aperture and the second clear optical aperture.

RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/341,079, filed Jan. 26, 2006 for “Apparatus For ShieldingProcess Chamber Port”, in the names of Fangli J. Hao, John E. Daugherty,and Allan K. Ronne (the “Prior Application”). The disclosure of thePrior Application is incorporated by reference. The benefit of thefiling date of the Prior Application is claimed under 35 U.S.C. Section120.

BACKGROUND

1. Field of the Invention

The present invention relates generally to semiconductor manufacturingand, more particularly, to apparatus for shielding access regions ofprocess chambers from electrical fields, wherein the access regionsallow access to semiconductor manufacturing chambers, the electricfields are applied to the chambers adjacent to the access regions, andaccess openings in the access regions provide access for exemplary gasinjectors and process analysis and measurement tools.

2. Description of the Related Art

Vacuum processing chambers have been used for etching materials fromsubstrates and for deposition of materials onto substrates, and thesubstrates have been semiconductor wafers, for example. U.S. Pat. No.6,230,651 to Ni et al. issued May 15, 2001 and assigned to Lam ResearchCorporation, the assignee of the present application, is incorporatedherein by reference and illustrates an opening, or port, in a dielectricwindow at a top of a processing chamber to provide access to an interiorof the processing chamber, for etching and other processing ofsemiconductor substrates, for example. For large diameter substrates,center gas injection was said to ensure uniform etching and deposition,for example, thus improving the access to such processing chambers.

However, as industry standards have increased, further improvements arerequired to provide even better access to such processing chambers. Forexample, there is a need to monitor the processes in the chambers, whichrequires chamber access in addition to access for gas supply. When themonitoring relies on optical data, a clear optical aperture must extendthrough the dielectric window. Difficulties arise, however, when theclear optical aperture is physically open to the chamber, because plasmamay form in the clear optical aperture. Such plasma formation relates toa threshold electric field strength required to initiate a plasma, whichthreshold strength is based on gas pressure in and the diameter of apassage, or bore, used to supply the gas to the chamber. Plasmaformation in a gas supply bore is generally reduced by reducing thediameter of the bore because the gas pressure tends to be controlled byprocess requirements. However, analysis by the applicants of the presentapplication indicates that when there is dual use of a clear opticalaperture (i.e., use for both optical and gas supply functions) the dualuse presents conflicting requirements. That is, for the aspect offacilitating monitoring the optical data, there is a need to increasethe diameter of the clear optical aperture. For example, in providingoptical access for spectroscopic observation of chamber processes, thediameter of the clear optical aperture must generally be not less thanabout one-half inch, for example, and it is highly desirable to use anaperture as large as possible. This diameter may be described as aminimum diameter that is required to enable proper access to the opticaldata that originates in the chamber, and is referred to herein as the“minimum diameter of the clear optical aperture”. This analysis alsoindicates that for the gas supply aspect of the dual use there is a needfor a relatively small diameter (significantly less than 0.5 inch) ofeach gas bore for gas supply to the chamber, for avoiding plasmaformation, for example. This analysis also indicates that to facilitatethe dual use, an optical window must be used to seal the clear opticalaperture so as to maintain a vacuum in the processing chamber, and thatthe optical window should be mounted at a location at which the strengthof the electric field is substantially reduced, to prevent sputtering ofthe optical window (which creates aluminum-containing contamination),and to prevent deposition onto the optical window. Thus, applicants'analysis indicates that there is not only the minimum diameter of theclear optical aperture in conflict with the need for small diameter gasbores, but a minimum length of the clear optical aperture necessary toavoid such contamination and damage to the optical window thatfacilitates the dual use.

This exemplary 0.5 inch minimum diameter of the clear optical aperturecompares to gas bore passages of 0.4 mm provided in shielded gas inletsdescribed, for example, in U.S. Pat. No. 6,500,299, issued 12/3/102 toMett, et al. Although multiple ones of such passages are providedthrough grains of dielectric materials such as ceramics, with the 0.4 mmdiameter size, such passages are not suitable for providing clearoptical access for the exemplary spectroscopic observation of chamberprocesses. Moreover, to mount such passages of a gas bore inside a metalcup and to insert the cup in the side wall of a process chamber asdescribed in the Mett et al. Patent, would undesirably subject the metalcup to the plasma in the chamber, for example, and introduce problems insealing the metal cup to the wall of the process chamber.

In view of the foregoing, there is a need for apparatus providingfurther improvements in accessing processing chambers. The need is forimproved ways to provide multiple access (e.g., gas supply and opticalaccess) to a process chamber. This need includes providing such accesswhen the optical access is subject to the conflicting requirements of arelatively large minimum diameter of the clear optical aperture (for theoptical function) and of a relatively small diameter of one or more gasbores for gas supply to the chamber (for avoiding plasma formation), forexample.

SUMMARY

Broadly speaking, embodiments of the present invention fill these needsby providing apparatus for shielding a process chamber port having dualzone and optical access features, the shielding being from electricalfields, wherein the access region allows access to a semiconductormanufacturing chamber, the electric fields are applied to the chamberadjacent to the access region, and access openings in the access regionsprovide access for exemplary gas injectors and process analysis andmeasurement tools. Such apparatus may include configurations of anaccess region of a process chamber to allow dual supply of process gasto the chamber, and to provide a first clear optical aperture foroptical access through a window of the chamber. Such apparatus may alsoprovide a combination of protection of a dual gas supply fitting and thefirst clear optical aperture from the electric field established by thecoil that surrounds the first clear optical aperture and the fitting. Ashield may be configured to extend into the window to provide suchprotection for a first section of the first clear optical aperture witha remaining second section of the first clear optical aperture extendingtoward the processing chamber. The remaining section may be protectivelycoated to provide such protection from the electric field and providethe minimum length of the clear optical aperture. A second clear opticalaperture is provided in the fitting to extend the first aperture awayfrom the electric field. The shield and additional coatings may protectthe second clear optical aperture from the electric field, and anoptical window may close the second clear optical aperture at a locationat which the strength of the electric field is substantially reduced, toprevent sputtering of the optical window (which createsaluminum-containing contamination), and to prevent deposition onto theoptical window.

Embodiments of the present invention may include a window for protectingan access region for access to a process chamber from an electric fieldgenerated adjacent to the process chamber window. The window may be awindow member configured with outer and chamber sides and an annulargroove extending from the outer side into the member parallel to theaxis. The annular groove defines a first section of the access region tobe protected from the electric field, and the window member is furtherconfigured with a clear optical aperture having an annular wallconfigured with a length between the outer side and the chamber side.The clear optical aperture may be partly surrounded by the annulargroove and may be further configured with a diameter. A coating of amaterial such as yttrium oxide is provided on the annular wall of theclear optical aperture. The annular wall with the coating having aninner coating diameter that is substantially the same as a value of thelength of the clear optical aperture in the window member.

An other embodiment of the present invention may include amulti-function process chamber window assembly for protecting an accessregion for access to a process chamber from an electric field generatedadjacent to the process chamber window, for admitting at least one gasto the process chamber, and for providing optical access to the chamber.An annular shield may have a length extending parallel to an axis of theregion and be fabricated from material adapted to substantially blockthe electric field. A window member is configured with respect to theaccess region axis, the member being configured with outer and chambersides and an annular groove extending from the outer side into themember. The groove defines a first section of the access region to beprotected from the electric field. The groove is configured to receive aportion of the shield to protect the first section of the access regionfrom the electric field. The groove receives the annular shield, and theshield extends out of the groove and away from the outer side so that asecond section of the access region is defined within the annularshield. The annular shield protects the second section from the electricfield. The window member is further configured with a first clearoptical aperture defined by a first annular wall configured with alength between the outer side and the chamber side. The first clearoptical aperture is partly surrounded by the annular groove, and thefirst clear optical aperture is further configured with a diameter forclear optical access. A coating is provided on the first annular wall.The first annular wall with the coating has an inner coating diameterthat is substantially the same as a value of the axial length of thefirst clear optical aperture. The coating protects the first clearoptical aperture from effects of the electric field so that theprotection extends past the shield in the annular groove to the chamberside of the window member.

Yet an other embodiment of the present invention may include amulti-function process chamber window assembly for protecting an accessregion for access to a process chamber from an electric field generatedadjacent to the process chamber window while providing at least two gasinlets to the process chamber and allowing optical access to thechamber. The assembly may include an integrated shield and gas supplyunit for protecting the access region from the electric field. The unitmay be configured with a thin annular protrusion at a first end and withan annular body that is thicker than the protrusion. The body may befurther configured to extend to a second end. The body may be furtherconfigured with a first annular wall defining a unit clear opticalaperture extending from the first end to the second end. A further bodyconfiguration may provide a first gas supply bore extending andintersecting the unit clear optical aperture adjacent to the first end.The body may be further configured with a first coupler and the unitfabricated from material adapted to substantially block the electricfield so that the unit clear optical aperture is protected from theelectric field. A window member of the assembly may be configured withouter and chamber sides and a groove extending from the outer side intothe member. The groove is configured to receive the thin annularprotrusion to protect a first section of the access region from theelectric field. The member may be further configured with a secondcoupler configured to cooperate with the first coupler to hold theprotrusion in the groove with the unit extending away from the outerside of the member so that a second section of the access region isdefined by and is protected by the body from the electric field. Thewindow member may be further configured with a window member clearoptical aperture having a second annular wall configured with a lengthbetween the outer side and the chamber side. The window member clearoptical aperture is partly surrounded by the thin annular protrusionreceived in the annular groove. The window member clear optical aperturemay be further configured with a diameter. A coating is provided on thesecond annular wall. The second annular wall with the coating has aninner coating diameter that is substantially the same as a value of theaxial length of the window member clear optical aperture. The coatingprotects the window member clear optical aperture from the electricfield.

It will be obvious, however, to one skilled in the art, that embodimentsof the present invention may be practiced without some or all of thesespecific details. In other instances, well known process operations havenot been described in detail in order not to obscure the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention will be readily understood byreference to the following detailed description in conjunction with theaccompanying drawings in which like reference numerals designate likestructural elements, and wherein:

FIG. 1 is a schematic view of an embodiment of an apparatus of thepresent invention for protecting an access region into a process chamberfrom an electric field;

FIG. 2A is a side cross-sectional view of an embodiment of a window ofthe present invention for protecting an access region into the processchamber from the electric field generated adjacent to the window;

FIG. 2B is a plan view of the window embodiment shown in FIG. 2A,illustrating a groove for a shield, a gas bore and a first clear opticalaperture;

FIG. 2C is a side cross-sectional view of another embodiment of thewindow of the present invention, illustrating a projection on thewindow;

FIG. 3A is a side cross-sectional view of the window embodiment of FIG.2B assembled with a shield and with an embodiment of a fitting separatefrom the shield;

FIG. 3B is a cross-sectional view taken along line 3B-3B in FIG. 3A,illustrating the assembled fitting of FIG. 3A configured with seals;

FIG. 3C is a cross-sectional view taken along line 3C-3C in FIG. 3A,illustrating the assembled fitting of FIG. 3A configured with anembodiment of an optical window;

FIG. 3D is a three-dimensional view of the fitting of FIG. 3A, showing aport for access to the embodiment of the optical window;

FIG. 4A is a side cross-sectional view of the assembled shield andembodiment of the fitting separate from the shield, illustrating anotherembodiment of the optical window;

FIG. 4B is a cross-sectional view taken along line 4B-4B in FIG. 4A,showing the FIG. 4A embodiment of the optical window;

FIG. 4C is a cross-sectional view taken along line 4C-4C in FIG. 4A,showing the FIG. 4A embodiment of the fitting with a gas inlet to gasbores of the fitting;

FIG. 5A is a side cross-sectional view showing the chamber windowembodiment of FIG. 2A assembled with a shield and multi-function fittingintegral with the shield, with one embodiment of an optical window nearthe chamber window; and

FIG. 5B is a side cross-sectional view of the shield and multi-functionfitting integral with the shield of FIG. 5A, illustrating the assembledfitting of FIG. 5A configured with the FIG. 4A embodiment of the opticalwindow.

Other aspects and advantages of embodiments of the invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of embodiments of the present invention.

DETAILED DESCRIPTION

Embodiments of an invention are described for apparatus, and for amulti-function process chamber window assembly, for protecting an accessregion for access to a process chamber from an electric field generatedadjacent to a window of the chamber. The protecting may be by shieldingaccess openings in the window from electrical fields, wherein theopenings allow multiple types of access to semiconductor manufacturingchambers. For an opening that is a gas bore for injecting process gasinto the chamber, the protection is from the electric field. For anopening that is a clear optical aperture providing optical access intothe chamber, the protection is also from effects of the electric field,and this protection may extend past a shield so that an entire length ofthe clear optical aperture is protected.

In one embodiment of the present invention, a window member isconfigured with respect to an access region axis, the member beingconfigured with an annular groove extending into the member parallel tothe axis. The annular groove may be configured to define a first sectionof the access region to be protected from the electric field. The windowmember may be further configured with a clear optical aperture having anannular wall extending co-axially with the axis and configured with anaxial length between the outer side and the chamber side. The clearoptical aperture may be partly surrounded by the annular groove and maybe further configured with a diameter. An Yttrium oxide coating may beprovided on the annular wall of the clear optical aperture. The annularwall with the coating may have an inner coating diameter that issubstantially the same as a value of the axial length of the clearoptical aperture.

In another embodiment of the present invention, a multi-function processchamber window assembly is provided for protecting an access region foraccess to a process chamber. The protection is from an electric fieldgenerated adjacent to the process chamber window. The window assemblymay admit at least one gas to the process chamber and may provideoptical access to the chamber. An annular shield having a lengthextending parallel to an axis region axis may be fabricated frommaterial adapted to substantially block the electric field. A windowmember may be configured with respect to the access region axis. Themember may also be configured with an annular groove extending parallelto the axis to define a first section of the access region to beprotected from the electric field. The groove may be configured toreceive a portion of the shield to protect the first section of theaccess region from the electric field. When the groove receives theannular shield, the shield may extend out of the groove so that a secondsection of the access region is defined within the annular shield. Theannular shield may be configured to protect the second section from theelectric field. The window member may be further configured with a firstclear optical aperture defined by a first annular wall extendingco-axially with the axis and configured with an axial length between theouter side and the chamber side. The first clear optical aperture may bepartly surrounded by the annular groove and may be further configuredwith a diameter for clear optical access. An exemplary Yttrium oxidecoating on the first annular wall may have an inner coating diameterthat is substantially the same as a value of the axial length of thefirst clear optical aperture. The exemplary Yttrium oxide coatingprotects the first clear optical aperture from effects of the electricfield so that the protection extends past the shield in the annulargroove to the chamber side of the window member.

FIG. 1 shows a schematic view of an apparatus 40 of the presentinvention for protecting an access region for access to a processchamber. The protection may be from an electric field generated adjacentto a window of the chamber. The access region may allow access to asemiconductor manufacturing process chamber, for example. The electricfield is applied to the process chamber adjacent to the access regionfor exemplary gas injectors and process analysis and measurement tools.FIG. 1 shows the apparatus 40 including a vacuum processing chamber 42having a substrate holder 44 providing a suitable clamping force to asubstrate 46. The top of the chamber 42 may be provided with adielectric window 48. One of many access openings, or ports, 50 is shownschematically as being provided in the window 48 to permit access to theinterior of the chamber 42.

FIG. 2A is an enlarged cross-sectional view showing the window 48 as aprocess chamber window with exemplary ports 50, and showing spacedvertical dot-dot-dash lines defining an exemplary cylindrical accessregion 52. The access region may thus be a three-dimensional volumewithin an exemplary hollow cylinder defined by the lines. In theembodiment of the access region 52 shown in FIG. 2A, the access region52 extends into the window 48, as described below. The portion of theaccess region extending into the window 48 may be referred to as a firstsection (see bracket 52-1). The access region is also shown extendingabove the window 48, and the portion of the access region 52 above thewindow 48 may be referred to as a second section (see bracket 52-2). Forother embodiments of the access region 52, similar lines may also defineanother three-dimensional shape, for example, and the other embodimentof the access region 52 would also be defined by such otherthree-dimensional shape.

FIG. 1 also schematically shows the chamber 42 provided with facilities54 that require access to the chamber 48 via the access region 52. Forexample, the facilities 54 may provide access to the chamber 42 forprocess analysis or measurement as described below, which may bereferred to as optical access. The facilities 54 may also provide accessto the chamber 42 to facilitate conducting deposition or etchingprocesses in the chamber 42, such as by supplying process gases to thechamber 42. As one example of the facilities 54, process gas may besupplied from a gas supply through the access region 52 into the chamber42. With a pump (not shown) reducing the pressure in the chamber 42 forthe deposition or etching processes, a source 58 of RF energy with animpedance matching circuit is connected to a coil 60 (see also FIG. 2A)to energize the gas in the chamber and maintain a high density (e.g.,10⁻¹¹ to 10⁻¹² ions/cm³) plasma in the chamber 42. The coil 60 may bethe type that inductively couples RF energy into the chamber 42 throughthe window 48 to provide the high density plasma for conducting thedeposition or etching processes in the chamber 42. During that coupling,the coil 60 generates an electric field (see exemplary lines 62, FIG.2A).

FIG. 2A shows that without the use of embodiments of a shield of thepresent invention, the electric field 62 may extend between turns of thecoil 60 above the top of the window 48 and may extend in the window 48through the ports 50. This generation of the electric field 62 withoutthe use of the shield embodiments of the present invention tends toinduce an undesired plasma in the ports 50 within the access region 52.For example, the tendency may be to induce the undesired plasma may beinduced in a bore through which the gas is supplied, or in a clearoptical aperture through which optical access is provided, as describedbelow. The undesired induced plasma may result in undesired depositionof particles on various parts within the process chamber 42, includingon the substrate, which lowers process yield.

The embodiments of the present invention may be used to substantiallyavoid the problems caused by such undesired plasma induced in the accessregion 52, while providing other advantages described below. Forexample, in the enlarged cross-sectional view of FIG. 2A, the window 48is shown as a multi-function process chamber window with exemplary ports50. In the FIG. 2A embodiment, the process chamber window 48 is shown inrelation to the access region 52 and to sections 52-1 and 52-2. Alongitudinal axis X of the window 48 is identified for reference. Thewindow 48 may also be described as a window member, and is shownconfigured with a groove 64, for example. The groove 64 extends in thewindow parallel to the axis X to a depth defined by an axial end. FIG.2B shows that the groove 64 may be configured with an annular shape thatthat extends circularly around the axis X. The groove 64 is thusconfigured to surround the access region.

In the use of the embodiment of the window 48 shown in FIG. 2A, thegroove 64 may receive a shield 66 (e.g., FIG. 3A) for protecting theaccess region 52. The protection is from the electric field 62 that isgenerated as described above. The field 62 is shown in FIG. 2A withoutthe shield embodiment of the present invention, the field 62 extendingadjacent to the window 48 in that the field 62 extends above the window,for example. One embodiment of the shield is identified as 66-1 in FIGS.3A, 3B, and 4A. Another embodiment of the shield is identified as 66-2in FIGS. 5A and 5B. References to the shield 66 apply to eachembodiment. The shield 66 may be fabricated from material adapted tosubstantially block the electric field 62 from entering the accessregion 52. Such material and other configuration of the shield 66provides an electric field-free condition within the shield (i.e.,within the access region 52). For the desired protection, the shield 66may be configured as a three-dimensional structure, such as acylindrical shield member 68 that has a shape that conforms to that ofthe access region 52, and the shield 66 is connected to an electricalground. FIG. 3A shows that with respect to embodiment 66-1, one end ofthe shield member 68 of the shield 66 is received in the groove 64 toencompass section 52-1 of the access region. Also, the shield member 68is shown configured to extend in the direction of the X axis out of thegroove 64. By reference to FIG. 2B it may be understood that when theshield member 68 is received in the groove 64, the shield member 68encompasses the access region 52. Also, the location of the bracket 52-2in FIG. 2C indicates that the shield member 68 encompasses the axiallength of the section 52-2 of the access region.

Referring to FIG. 2A, the window 48 is shown further configured with anouter side 70 that is outside of the chamber 42, and with a chamber side72 that is inside the chamber. The groove 64 extends into the window 48through the outer side. FIGS. 2A and 2B show the window configured witha plenum 74 that may distribute process gas to the chamber via aplurality of nozzles 76. The plenum is configured with an annular shapehaving a diameter less than that of the groove 64. The plenum extends toa depth about half way between the outer side 70 and the chamber side72. FIG. 2B shows (in dashed lines) an exemplary eight of the nozzles76, which intersect (and thus are connected to) the plenum and extend tothe chamber side 72, which is shown as a flat surface parallel to theouter side 70. FIG. 2A shows that a portion of the plenum 74 isencompassed by the groove 64, and is thus in the access region 52.According to the particular process to be conducted in the chamber 42,the window 48 may be made from quartz or ceramic, for example. In theembodiment described herein, the window may be made from ceramic, suchas aluminum oxide, which has desired characteristics of tensilestrength, thermal conductivity, and chemical resistance. The window mayalso be made from aluminum nitride, which has desired characteristics oftensile strength and thermal conductivity.

FIGS. 2A and 2B also show the window 48 further configured with a clearoptical aperture 78 that may be identified as a first (or window) clearoptical aperture to distinguish from other clear optical aperturesdescribed below. The first clear optical aperture 78 is configured withan annular wall 80 extending co-axially with the axis X and configuredwith an axial length L (FIG. 2A) between side 70 and side 72. The firstclear optical aperture 78 is partly surrounded by the annular groove 64,and may further be configured with a diameter D1. The diameter D1 may beselected to provide desired access to the chamber, such as opticalaccess by which an observation device (not shown) may view into thechamber for spectroscopy, for example. This may include infraredspectroscopy, for example. Also, plasma properties such as ion flux,e.g., may be measured, or the composition of deposits in the chamber maybe determined. For use in the above-described spectroscopic observation,for example, the diameter D1 must be generally not less than aboutone-half inch. This diameter D1 may correspond to the above-describedminimum diameter of the clear optical aperture, that is the minimumdiameter that is required to enable proper access to the optical datathat originates in the process chamber. The first clear optical aperture78 may also be used to introduce process gas into the chamber 48. Theprocess gas introduced by the first clear optical aperture 78 may bedifferent from the gas supplied by the plenum 74, for example, and mayvary according to the type of processing to be done in the chamber.

FIGS. 2A and 2B also show the annular wall 80 provided with a layer,such as a coating, 82. The coating 82 has an inner coating diameter thatis substantially the same as a value of the axial length L of the clearoptical aperture 78. The coating 82 may be of a type that does notreadily combine with chamber gases, and especially not with fluorine.For example, the clear optical aperture 78 is open to the chamber, thusthe plasma that is generated in the chamber 42 may enter the clearoptical aperture 78. Even though the shield 66 and other shieldembodiments (described below) are configured to substantially reduce thestrength of the electric field 62 that may extend across the clearoptical aperture 78, the reduced-strength electric field may cross clearoptical aperture 78 and may interact with the plasma. Without thecoating 82, an aluminum-containing ceramic such as aluminum oxide oraluminum nitride, could react with fluorine, for example, to formaluminum fluoride, which will form particles easily removed from thewall 80 during processing inside the chamber, such as by flaking off,which particles would enter the chamber 48. Embodiments of the clearoptical aperture 78 having the coating 82 of the type that does notreadily combine with chamber gases include coating materials havinghigher chemical resistance, e.g., to fluorine, than the chemicalresistance of the underlying ceramic material. Thus, relatively few ofthe exemplary aluminum fluoride particles are formed and enter thechamber 48, such that process yield may increase.

Exemplary materials for the coatings 82 that are of the type that do notreadily combine with chamber gases, include: yttrium oxide; yttriumoxide with pores sealed with methacylate ester or sealed with anotherpolymer such as PTFE; or cerium oxide; or zirconium oxide; oryttria-stabilized zirconia; or thermally-sprayed aluminum oxide. Tosputter a coating 82 of, for example, yttrium oxide requires ionbombardment of high energy, for example, and with the higher chemicalresistance, such coating 82 on the first clear optical aperture 78results in the low rate of aluminum fluoride formation.

An unexpected aspect of the chamber window 48 relates to theabove-described minimum diameter of the clear optical aperture. There isan inverse relationship between the value of such diameter D1 and theability of the window 48 of a minimum thickness to withstand forces athigh vacuum. Also, to meet the requirements of the above-describedoptical access, diameter D1 must not be less than the minimum diameterof the clear optical aperture. Thus the thickness of the window 48 maybe the minimum required for adequate strength when the diameter D1 has avalue of the minimum diameter of the clear optical aperture. With thisin mind, the exemplary 0.5 inch minimum diameter D1 of the clear opticalaperture is also a value of an acceptable thickness L of the window 48,and is also an acceptable diameter for the application of the coating 82to the entire surface of the wall 80. For example, a torch plasmaprocess may be performed in Argon using an yttrium oxide powder. Thetorch process generates blobs of powder that splat on the surface to becoated. Ideally, the torch plasma process is directed at an angle ofninety-degrees to the surface to be coated. Because the clear opticalaperture 78 has the cylindrical wall 80, the ninety-degree direction isnot possible. A limitation of the process is to not direct the processat less than 45 degrees. With a 0.5 inch diameter D1 configuration ofthe optical aperture 78 of the window 48, and at the 45 degreedirection, the torch plasma process is effective to direct the coatingof yttrium oxide 0.25 inches into the cylinder defined by the wall 80and have proper adhesion of the coating. As a result, by directing thecoating of yttrium oxide 0.25 inches into each end of the cylinderdefined by the wall 80, the entire 0.5 inch length L of the cylinderdefined by the wall 80 may be provided with the coating 82, and at thesame time the diameter requirements of the clear optical apertures forthe exemplary spectroscopy, and the window strength requirements, aremet.

FIG. 2C shows another embodiment of the window, or window member, 48 inwhich the chamber side 72 of the window member may be configured with aprojection 90 defined by an axially-extending surface 92 and a flatsurface 94 parallel to the chamber side. The nozzles 76 intersect theaxially-extending surface 92 and provide improved distribution of thegas into the chamber 48.

FIG. 3A shows a further configuration of the plenum 74 for assisting inalignment of the window 48 during assembly with an embodiment 100-1 of amulti-function fitting 100. The window member 48 with the shield 66 andthe fitting 100 combine to define an assembly. The plenum 74 isconfigured with a first pin hole, or pin bore, 102 centered on the axisof the annular plenum. The first pin bore has a diameter larger than thewidth of the plenum 74 and defines a location for alignment with thefitting 100. The fitting is configured with a body 101 provided with agas bore, or conduit, 104 that is configured to supply process gas tothe plenum 74. The body 101 is further configured with a second pinhole, or pin bore, 106 coaxial with the gas bore 104, and having adiameter larger than the diameter of the gas bore 104. The diameter ofthe bore 106 may be equal to the diameter of the first pin bore 102. Inassembly of the window 48 with the fitting 100, an alignment pin 108 maybe inserted into the second pin hole 106, and the first pin hole 102aligned with the pin 108 to properly locate the fitting 100 relative tothe window 48.

In the above description of FIG. 3A, the embodiment 66-1 of the shield66 was said to be received in the groove 64 to encompass section 52-1 ofthe access region. The shield member 68 was said to be shown extendingin the direction of the X axis out of the groove 64 to encompass theaxial length of the section 52-2 of the access region (as shown by thelength of the bracket 52-2 in FIG. 3A). With this in mind, it may beunderstood that the outer surface 70 outside of the shield 66-1 may beprovided with an annular-shaped thin flat shield 109 to block componentsof the electric field 62 that are parallel to the axis X. The flatshield 109 may be fabricated from the same material as the shield 66,for example. The flat shield 109 is thus mounted under the coil 60 onthe outer side 70 of the window 48 and extends outwardly from the shield66-1. With the flat shield 109 mounted and with the pin 108 used toproperly locate the fitting 100 relative to the window 48, the shield66-1 may also be located and secured relative to the window 48. FIG. 3Ashows the shield 66-1 with the cylindrical shield member 68 shaped toconform to that of the access region 52. FIG. 3A also shows the shield66-1 received in the groove 64 encompassing section 52-1 of the accessregion, and extending in the direction of the X axis out of the groove64 to encompass the access region 52, including the axial length ofsection 52-2 of the access region. The shield 66-1 is configured with alower mount flange, or first coupling, 110 cooperating with the flatshield 109 and with a fastener to secure the shield member 86 on theflat shield that is on the window member 48. For ease of illustration,the lower mount flange 110 is shown in FIG. 3A only once, it beingunderstood that the flange 110 may be provided at three, for example,locations around the bottom of the shield 66-1.

FIG. 4A shows a top of the shield 66-1 adjacent to a top of the fitting100-1. The shield 66-1 is there shown configured with an upper mountflange, or second coupling, 112 cooperating with a fitting mount 114 anda fastener to secure the shield member 86 to the fitting 100-1. Therespective coupling 112 and mount 114 are pulled together by thefastener so that the fitting is pressed downwardly onto the windowmember 48, as is described in more detail below. For ease ofillustration, the flange 112 is shown in FIG. 4A only once, it beingunderstood that the flange 112 may be provided at three, for example,locations around the top of the shield 66-1. As mounted and secured, theshields 66-1 and 109 are in position to protect the access region 52from the electric field 62. Also as mounted and secured, the fitting100-1 is in position to admit at least one gas to the window member 48for injection into the process chamber 42, and to provide optical accessthrough the first clear optical aperture 78 to the chamber. The fitting100-1 is thus a multi-function fitting received within the secondsection 52-2 of the access region 52 defined by the shield 66-1 forprotection from the electric field.

FIG. 3A shows one embodiment 100-1 of the fitting in which the body 101is configured with a second clear optical aperture 116 having a secondannular wall 117 extending co-axially with the axis X and verticallyaligned with the coated first clear optical aperture 78. The secondclear optical aperture 116 serves both to supply gas to the first clearoptical aperture 78 and to allow clear optical access to the chamber 42through the first clear optical aperture 78, e.g., as described abovewith respect to the exemplary spectroscope (not shown) mounted above thechamber 42 out of the electric field. To facilitate this gas supply, thefitting body 101 is further configured with a gas supply bore, orconduit, 118 initially extending parallel to the axis X and then anglesto intersect the second clear optical aperture as described below.

It may be understood that the chamber 42 is operated at a vacuum, suchas in a range of 5-400 milliTorr. To maintain the vacuum, the fitting100-1 is sealed to the window member 48 by a first seal structure 120that may include seals 122 and 124. In a general sense, the sealstructure 120 is between the fitting 100-1 and the window member 48. Theseal structure 120 is configured so that in response to the upper andlower couplers 110, 112, and 114 urging the fitting 100-1 toward thewindow member 48, the seal structure 120 provides an air-tight seal ofthe fitting 100-1 to the window member 48. Thus, gas flows from the gassupply bore 104 into the annular plenum 74 separately from therespective first and second clear optical apertures 78 and 116. Also,gas flows from the second clear optical aperture 116 into the firstclear optical aperture 78 separately from the gas supply bore 104 andfrom the annular plenum 74. Also, unwanted gases (e.g., atmospheric) donot flow into the chamber.

The seal structure 120 is configured to be mounted in a lower, orwindow, end 126 of the fitting 100. The end 126 is configured with twospaced annular recesses 128, spaced radially outward from the secondclear optical aperture 116. The seals 122 and 124 may be configured witha seal member, such as an O-ring or pad, 130 that may be mounted in eachrecess 128 and squeezed by the fitting 100-1 that is urged toward thewindow member 48.

FIG. 3A also shows the lower end 126 configured with one embodiment132-1 of an optical window assembly 132, and FIG. 4A shows an upper, orsecond, end 134 of the fitting 100-1 configured with another embodiment132-2 of the optical window assembly. FIG. 3A shows the optical windowassembly 132-1 configured with a seat 136 adjacent to the first sealstructure 120 and co-axial with the access region axis X. The seat 136is configured with a recess 138 to receive a second seal, such as anO-ring, 140. The assembly 132-1 further includes an optical window 142received in (mounted on) the seat 136. With respect to the optical datathat is received from the chamber 42, the optical window 142 may have anoptical characteristic of transmitting that optical data out of thesecond clear optical aperture and into a suitable optical unit, such asa collimator (not shown) for further transmission to the exemplaryspectrometer (not shown). For ease of illustration, FIGS. 3A and 3C showthe portion of the window 142 to the right of the axis X, it beingunderstood that the window 142 is disk-like (circular). The second seal140 between the seat 136 and the optical window 142 prevents gas fromleaking into and past the second clear optical aperture 116 into thefirst clear optical aperture 78, while allowing optical access throughthe second clear optical aperture 116 and through the first clearoptical aperture 78 into the chamber 42. A clamp 144 may be used to holdthe window 142 against the second seal 140 and the seat 136. To provideaccess to the optical window 142, FIGS. 3A and 3D show that the wall 117of the fitting 100-1 is further configured with at least one access port150. The port 150 is an opening in the body 101 and is located on a sideof the optical window 142 that is away from the window member 48. As maybe necessary for such access to the window 142 or the clamp 144, manyports 150 may be provided in the wall 117.

By reference to FIG. 4A it may be understood that in one embodiment ofthe fitting 100-1 with the embodiment 132-2 of the optical windowassembly 132, the second clear optical aperture 116 is configured sothat the second annular wall 117 is clear, e.g., unobstructed and open,from the low end 126 (that is adjacent to the window member 48) to theupper end 134 (spaced from the window member). For the other embodiment132-2 of the optical window assembly 132, the second end 134 of thefitting 100 is further configured with a third sealing seat 152. Thestructure of the assembly 132-2 is similar to that of the assembly132-1, and includes the seat 152 configured with a recess 154 to receivea second seal, such as an O-ring, 156. FIGS. 4A and 4B show the assembly132-2 further configured with an optical window 158 received in (mountedon) the seat 152. The second seal 156 between the seat 152 and theoptical window 158 prevents gas from leaking into and past the secondclear optical aperture 116 into the first clear optical aperture 78,while allowing optical access through the second clear optical aperture116 and through the first clear optical aperture 78 into the chamber 42.A clamp 160 may be used to hold the window 158 against the second seal156 and the seat 152.

Because the second clear optical aperture 116 is open from the low end126 to the upper end 134 of the fitting 100, plasma from the chamber 48may flow through the first clear optical aperture 78 and into the secondclear optical aperture 116. As described above concerning the firstclear optical aperture 78, even though the shield 66-1, the shield 109,and other shield embodiments (described below) are configured tosubstantially reduce the strength of the electric field 62 that mayextend across the fitting and the second clear optical aperture 116, theelectric field 62 of some small strength may cross second clear opticalaperture 116 and interact with the plasma. To protect the wall 117 fromthe effects of such low strength electric field 62, FIG. 4A also showsthe annular wall 117 provided with protective layers, such as secondcoatings 162. Each of the coatings 162 has an inner coating diameterthat is substantially the same as a value of the coating diameter D1 ofthe first clear optical aperture 78. The coatings 162 may be the sametype as coating 82, and may be deposited on the wall 177, all asdescribed above. Thus, about one-half inch at each end 134 and 126 ofthe wall 117 may be provided with the coatings 162. As noted above,without the coatings 162 an exemplary aluminum-containing ceramic willreact with fluorine to form aluminum fluoride, which will form particleseasily removed from the wall 80 during processing inside the chamber,such as by flaking off, which particles would enter the chamber 48. Inthe embodiment of the second clear optical aperture 116 having thecoatings 162, e.g., of yttrium oxide that requires ion bombardment ofhigh energy to be sputtered, in the second clear optical aperture 116there is a low rate of aluminum fluoride formation adjacent to thecoatings 162, which may have a combined one inch of the wall 117protected from the effects of the low strength electric field 62 in theabove exemplary configuration with D1 of 0.5 inch. In other words, onecoating 162 may be a second Yttrium oxide coating on the second annularwall 117, and the second coating may extend from the first end 126 for adistance about equal to the diameter of the second annular wall 117.Also, the other coating may be a third Yttrium oxide coating on thesecond annular wall 117, and the second coating may extend from thesecond end 134 for a distance about equal to the diameter of the secondannular wall 117.

FIGS. 3A and 4A show the fitting body 101-1 further configured with thesecond gas supply bore 118 extending parallel to the axis X, radiallyoutward from the axis X and from the second clear optical aperture 116,but radially inward of the first bore 104. FIG. 3A shows the bore 118configured with an angle section directed toward and intersecting thesecond clear optical aperture 116. The angle section avoids interferenceby the bore 118 with the first seal structure 120, for example. Thesecond bore 118 may also be a single bore sized to supply process gas tothe second clear optical aperture 116 and then to the first clearoptical aperture 78 for distribution into the chamber 48.

For the embodiment of the optical window assembly 132-1 configured withthe seat 136 adjacent to the first seal structure 120, the window 142and the bores 104 and 118 are configured to avoid interference with eachother. In this case, the bores 104 and 118 are oriented in the body 101radially outside of the window 142, i.e., away from the axis X enough toextend vertically in the body 101-1 past and not intersect the window142. Also, prior to assembly of the fitting 100-1 with the window member48, the lower end 126 of the wall 117 of the fitting 101-1 may beprovided with the coating 162, which may be the second coating 162described above. The axial length of such second coating 162 may extendfrom the end 162 to the location of the seat 136.

Further, consistent with the above-described minimum length from thewindow 48 to the optical window 142 (as necessary to avoid the notedcontamination and damage to the optical window 142), the optical window142 may be at an axial location between the ends 126 and 134. That axiallocation may be selected according to the process to be performed in thechamber 42, for example, which may include the strength of the electricfield 62. It may be understood that the process, for example, may besuch as to make it necessary to locate the optical window 142 at alocation at which the strength of the electric field is substantiallyreduced, to prevent sputtering of the optical window (which createsaluminum-containing contamination), and to prevent deposition onto theoptical window. In that event, the embodiment 100-1 of the fitting maybe provided with the embodiment 132-2 of the optical window, i.e., theoptical window 158 as shown in FIG. 4A. Further, in the implementationof the embodiment 132-2 the fitting 100-1 may have an axial length fromend 126 to end 134 of from about three to about six inches, and theshield 66-1 may have a corresponding axial length 52-2 above the window48, for example. The optical window 158 may thus be located spaced fromthe window 48, where the strength of the electric field 62 issubstantially reduced, so that there are minimal amounts of theabove-described contamination and damage to the optical window 158. Theend 134 with the optical window 158 is thus spaced from the first end126 to locate the seat 154 (and thus the optical window 158) where thestrength of the electric field is substantially reduced as compared tothe electric field strength adjacent to the process chamber window 48.This optical window location may thus provide the above-describedminimum length from the window 48 to the optical window 158.

FIG. 4A shows a gas inlet 180 that for the two bores 104 and 118, forexample, is a dual gas inlet. The inlet 180 may be secured (as bysuitable fasteners) to the fitting to align inlet bores with horizontalextensions of the bores 104 and 118. For embodiments of the presentinvention with a requirement for more than two gases, the inlet 180 maybe configured with more inlet bores and the fitting configured with morebores of the type of bores 104 or 118, for example.

FIGS. 5A and 5B illustrate another embodiment 100-2 of the fitting 100assembled to the window 48 shown in FIG. 2A. The fitting 100-2 isconfigured with the fitting functions and the functions of the shield 66integral, or integrated into one piece, so that the fitting may bereferred to as an integrated shield and gas supply unit, identified byreference number 100-2. Reference numbers used above that refer tosimilar structure are used below to describe the unit 100-2, and a “-2”is used to refer to structure unique to the unit 100-2. The integralshield aspects (similar to shield 66) are referred to as 66-2. The body101-2 of the unit 100-2 is configured with the shield 66-2. The shield66-2 is configured with a thin annular shield protrusion 190 at thefirst (lower) end 126. The groove 64 of the window 48 may receive theshield protrusion 190 for protecting the access region 52, and theprotection is that described above in re FIG. 2A.

The unit 101-2 may be fabricated from material adapted to substantiallyblock the electric field 62 from entering the access region 52. Suchmaterial, and other configuration of the unit 101-2 (i.e., theprotrusion 190) promote an electric field-free condition within theunit. For the desired protection, above the protrusion 190 the unit100-2 is configured as a solid cylinder member 68-2 configured to bereceived in the access region 52 and to provide the gas supply andoptical access described above. FIG. 5A shows that with respect toembodiment 66-2, the protrusion 190 is received in the groove 64 toencompass section 52-1 of the access region. Also, the unit 100-2 isshown configured to extend in the direction of the X axis out of thegroove 64 to encompass the axial section 52-2 (FIG. 2C) of the accessregion.

For clarity of illustration, FIG. 5A does not show the configurationshown in FIG. 3A of the plenum 74 and window 48 for assisting inalignment of the window 48 during assembly with embodiments of amulti-function fitting 100. However, in the manner shown in FIG. 3A, theunit 100-2 and window 48 may be configured with the first pin hole 102,and with the body 101 provided with the gas bore 104 configured tosupply process gas to the plenum 74, with the second pin hole 106, andthe alignment pin 108 to properly locate the fitting 100 relative to thewindow 48. The embodiment 66-2 of the shield 66 is thus received in thegroove 64 to encompass section 52-1 of the access region, and the body101 of the unit 100-2 extends in the direction of the X axis out of thegroove 64 to encompass the axial section 52-2 of the access region. Thepin 108 may be used to properly locate the fitting 100 relative to thewindow 48, and the shield 66-2 (via the protrusion 190) may also belocated and placed in the groove 64. FIG. 5A shows the shield 66-2 withthe protrusion 190 around the section 52-1 of the access region 52. FIG.5A also shows that with the shield 66-2 received in the groove 64encompassing section 52-1 of the access region, the body 101-2 extendsin the direction of the X axis encompass the axial section 52-2 (FIG.2A) of the access region. The body 101-2 is configured with a lowermount flange 200 configured to cooperate with the flat shield 109 and afastener to secure the body 101-2 to the window member 48. The flange200 and window 48 are pulled together by the fastener so that thefitting is pressed downwardly onto the window member 48 so that thevacuum is maintained by the same first seal structure 120, as describedabove.

As mounted and secured, the integral shield 66-2 is also in position toprotect the access region 52 from the electric field 62. Also as mountedand secured, the unit 100-2 is in position to admit at least one gas tothe window member 48 for injection into the process chamber 42, and toprovide optical access through the first clear optical aperture 78 tothe chamber. The unit 100-2 is thus also a multi-function fitting andshield received within the second section 52-2 of the access region 52for protection from the electric field.

FIG. 5A shows an embodiment of the unit 100-2 in which the body 101-2 isconfigured with the second clear optical aperture 116 that may be thesame as that used in FIG. 3A. The body 101-2 is further configured withthe gas supply bore 104 extending parallel to the axis X and verticallyaligned with the annular plenum 74, and with the bore 118 to supply gasto the second clear optical aperture 116. FIG. 5A shows the lower end126 also configured with one embodiment 132-1 of the optical windowassembly 132, as described above. FIG. 5B shows the body 101-2configured so that the upper end 134 of the body 101-2 is configuredwith the other embodiment 132-2 of the optical window assembly 132, alsoas described above. Thus, the embodiment 100-1 of the fitting may beprovided with the embodiment 132-2 of the optical window, i.e., theoptical window 158 as shown in FIG. 4A. In the implementation of theembodiment 132-2 the fitting 100-1 may have an axial length from end 126to end 134 as described above so that the optical window 158 is locatedwhere the strength of the electric field 62 is substantially reduced,which may result in minimal amounts of the above-described contaminationand less damage to the optical window 158. Such optical window locationmay be from about three inches to about six inches from the window 48,for example. It may be understood that the second clear optical aperture116 is thus configured so that the second annular wall 117 is clear,e.g., unobstructed and open, from the low end 126 (that is adjacent tothe window member 48) to the upper end 134 (spaced from the windowmember), and is also provided with the coatings 162.

FIG. 5B shows the gas inlet 180 for the two bores 104 and 118, forexample, to provide a dual gas inlet. The inlet 180 may be secured (asby suitable fasteners) to the fitting to align inlet bores withhorizontal extensions of the bores 104 and 118. For embodiments of thepresent invention with a requirement for more than two gases, the inlet180 may be configured with more inlet bores and the fitting with morebores of the type of bores 104 or 118, for example.

In review, embodiments of the present invention satisfy the describedneeds by providing further improvements in accessing processing chamber42, where multiple access is provided by the window member 48 with theclear optical aperture 78 and with the dual supply gas bores 104(feeding plenum 74) and 118 (for gas supply to aperture 78). This needis met, for example, by overcoming the conflicting requirements for therelatively large minimum diameter of the clear optical aperture 78 forthe optical function and for a relatively small diameter of one or moregas bores 104 or 118 (or of the plenum 74) for gas supply to the chamber42 to avoid plasma formation, for example. The conflicting requirementsare overcome by the combination of protection of the dual gas supplybores 104 and 118 (and plenum 74) and the first clear optical aperture78, protection being from the electric field 62 established by the coil60 that surrounds the clear optical aperture 78. In the embodiments, theshield 66 is configured to extend into the window 48 to provide suchprotection for the first section 52-1 of the clear optical aperture 78.The remaining second section 52-2 of the clear optical aperture 78 maybe provided with the protective coating 82 to provide such protectionfrom the reduced-strength electric field 62.

The protective coating 82 (such as yttrium oxide) provided on theannular wall 80 of the clear optical aperture 78 is facilitated by theinner coating diameter D1 substantially the same as the value of theaxial length L of the clear optical aperture. Because the exemplary 0.5inch minimum diameter D1 of the clear optical aperture 78 is also avalue of an acceptable thickness L of the window 48, and because boththe diameter D1 and length L are also acceptable for applying thecoating 82 to the entire surface of the wall 80 (e.g., by the torchplasma process), the thickness of the window 48 may be reduced to thevalue of L, the requirements of the minimum diameter of the clearoptical aperture 78 may be met, and the dual shielding and coatingprotection of the first clear optical aperture 78 is facilitated.

In addition, for providing optical access for exemplary spectroscopicobservation of chamber processes, embodiments of the present inventiondescribed with respect to FIGS. 4A and 5B enable location of the opticalwindow 158 where the strength of the electric field 62 is substantiallyreduced, which may result in minimal amounts of the above-describedcontamination and less damage to the optical window 158, and allowprovision of the minimum diameter of the clear optical aperture 78 ofthe exemplary one-half inch.

Further, for situations (e.g., process) that permit the optical window142 (FIGS. 3A and 5A) to be located nearer to the end 126, this locationis within both embodiments 66-1 and 66-2 of the shield 66, such that theoptical window 142 is protected by these shields 66 and the wall 117 isprotected by the coating 162 (shown in FIGS. 4A and 5B) as describedabove.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. For example and not limitation, while the shield 66 hasbeen described as being cylindrical, the shield 66 may be configuredwith other three-dimensional shapes. Exemplary shield cross-sectionalconfigurations include square and oval.

Accordingly, the present embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalents of the appended claims.

1. A window for protecting an access region for access to a processchamber from an electric field generated adjacent to the process chamberwindow, the window comprising: a window member configured with outer andchamber sides and a groove extending from the outer side into the memberparallel to the axis, the groove defining a first section of the accessregion to be protected from the electric field, the window member beingfurther configured with a clear optical aperture having an annular wallconfigured with an axial length between the outer side and the chamberside, the clear optical aperture being partly surrounded by the groove,the clear optical aperture being further configured with a diameter; anda coating on the annular wall of the clear optical aperture, the annularwall with the coating having an inner coating diameter that issubstantially the same as a value of the axial length of the clearoptical aperture, the material from which the coating is fabricatedbeing taken from the group consisting of cerium oxide, zirconium oxide,yttria-stabilized zirconia, thermally-sprayed aluminum oxide, yttriumoxide, and yttrium oxide having pores, wherein the pores are sealed witha material taken from the group consisting of methacylate ester andpolymer.
 2. A process chamber window as recited in claim 1, wherein thewindow member is further configured from one piece of ceramic.
 3. Aprocess chamber window as recited in claim 1, wherein the window memberis further configured with an annular gas plenum and a plurality ofnozzles, each of the nozzles being connected to the annular gas plenum.4. A process chamber window as recited in claim 1, wherein the chamberside of the window member is configured with a flat surface.
 5. Aprocess chamber window as recited in claim 3, wherein the chamber sideof the window member is configured with a projection defined by anaxially-extending surface and a flat surface parallel to the chamberside, the nozzles intersecting the axially-extending surface.
 6. Amulti-function process chamber window assembly for protecting an accessregion for access to a process chamber from an electric field generatedadjacent to the process chamber window, for admitting at least one gasto the process chamber, and for providing optical access to the chamber,the assembly comprising: a three-dimensional shield having a lengthextending parallel to an access region axis and being fabricated frommaterial adapted to substantially block the electric field; a windowmember configured with respect to the access region axis, the memberbeing configured with outer and chamber sides and a groove extendingfrom the outer side into the member, the groove extending parallel tothe axis, the groove defining a first section of the access region to beprotected from the electric field, the groove being configured toreceive a portion of the shield to protect the first section of theaccess region from the electric field, the groove receiving the portionof the shield so that the shield extends out of the groove and away fromthe outer side so that a second section of the access region is definedwithin the shield, the shield protecting the second section from theelectric field, the window member being further configured with a firstclear optical aperture defined by a first annular wall extendingco-axially with the axis and configured with an axial length between theouter side and the chamber side, the first clear optical aperture beingpartly surrounded by the groove, the first clear optical aperture beingfurther configured with a diameter for clear optical access; and a firstcoating on the first annular wall, the first annular wall with thecoating having an inner coating diameter that is substantially the sameas a value of the axial length of the first clear optical aperture, thecoating protecting the first clear optical aperture from effects of theelectric field so that the protection extends past the shield in thegroove to the chamber side of the window member, the material from whichthe first coating is fabricated being taken from the group consisting ofcerium oxide, zirconium oxide, yttria-stabilized zirconia,thermally-sprayed aluminum oxide, yttrium oxide, and yttrium oxidehaving pores, wherein the pores are sealed with a material taken fromthe group consisting of methacylate ester and polymer.
 7. An assembly asrecited in claim 6, the assembly further comprising: a multi-functionfitting received within the second section of the access region definedby the shield for protection from the electric field, the fitting beingconfigured with a second clear optical aperture having a second annularwall extending co-axially with the axis and aligned with the coatedfirst clear optical aperture to supply gas to the first clear opticalaperture and allow clear optical access to the chamber through the firstand second clear optical apertures.
 8. An assembly as recited in claim7, wherein: the window member is configured with a plenum extending fromthe outer side into the member and with a plurality of nozzles extendingfrom the plenum to the chamber side to supply gas to the chamber; andthe fitting is further configured with a gas supply bore extendingparallel to the axis and aligned with the plenum.
 9. An assembly asrecited in claim 8, the assembly further comprising a seal structurebetween the fitting and the window member.
 10. An assembly as recited inclaim 9, wherein: the shield is configured with opposite ends, each ofthe ends being configured with a coupler, one coupler securing theshield to the window member with the shield in the groove, the othercoupler securing the fitting to the shield so that the fitting is urgedtoward the window member; and the seal structure is configured so thatin response to the other coupler urging the fitting toward the windowmember the seal structure seals to the window member so that gas flowsfrom the gas supply bore into the plenum separately from the first andsecond clear optical apertures and gas flows from the second clearoptical aperture into the first clear optical aperture separately fromthe gas supply bore and the plenum.
 11. An assembly as recited in claim7, wherein the fitting is configured with an end, the assembly furthercomprising: a first seal structure between the end of the fitting andthe window member; and wherein the end is configured with a seatadjacent to the seal structure and co-axial with the access region axis;the assembly further comprising an optical window received in the seatand a second seal structure between the seat and the optical window toprevent gas from leaking past the second optical aperture while allowingoptical access through the second clear optical aperture and the firstclear optical aperture into the chamber.
 12. An assembly as recited inclaim 11, wherein the fitting is further configured with at least oneaccess port in the second annular wall to provide access to the opticalwindow, the port being located on a side of the optical window that isaway from the window member.
 13. An assembly as recited in claim 7,wherein the second clear optical aperture is configured so that thesecond annular wall is open from a first end that is adjacent to thewindow member to a second end spaced from the window member, the secondend of the fitting being further configured with a sealing seat, theassembly further comprising: the assembly further comprising an opticalwindow received in the sealing seat and a second seal structure betweenthe seat and the optical window to prevent gas from leaking past thesecond optical aperture while allowing optical access through the secondclear optical aperture and the first clear optical aperture into thechamber; the spacing of the second end from the window member enablinglocation of the optical window where the strength of the electric fieldis substantially reduced as compared to the electric field strengthadjacent to the process chamber window.
 14. An assembly as recited inclaim 13, the assembly further comprising: a second coating on thesecond annular wall, the second coating extending from the first end fora distance about equal to the diameter of the second annular wall; and athird coating on the second annular wall, the second coating extendingfrom the second end for a distance about equal to the diameter of thesecond annular wall; the second and third coatings being fabricated fromthe same material as the first coating.
 15. An assembly as recited inclaim 6, wherein: the window member is configured with an annular plenumextending from the outer side into the member and with a plurality ofnozzles extending from the annular plenum to the chamber side to supplygas to the chamber; the assembly further comprises a multi-functionfitting received within the second section of the access region definedby the shield for protection from the electric field, the fitting beingconfigured with a second clear optical aperture having a second annularwall extending co-axially with the axis and aligned with the coatedfirst clear optical aperture to supply gas to the first clear opticalaperture and allow clear optical access to the chamber through the firstand second clear optical apertures, the fitting is further configuredwith a gas supply bore extending parallel to the axis and aligned withthe annular plenum; the shield is configured with opposite ends, each ofthe ends being configured with a coupler, one coupler securing theshield to the window member with the shield in the groove, the othercoupler securing the fitting to the shield so that the fitting is urgedtoward the window member, the end configured with the one coupler beingconfigured with a seat that is co-axial with the access region axis; andthe assembly further comprises a first seal structure between the windowmember and the one end of the fitting that is configured with the onecoupler, the first seal structure sealing the gas supply bore to theplenum, an optical window received in the seat, a second seal structurebetween the seat and the optical window to prevent gas from leaking pastthe second optical aperture while allowing optical access through thesecond clear optical aperture and the first clear optical aperture intothe chamber.
 16. An assembly as recited in claim 15, wherein: thefitting is further configured with a second gas supply bore extendingrelative to the axis to supply gas to the first clear optical aperture;the first seal structure seals the second gas supply bore to the firstclear optical aperture when the fitting is urged toward the windowmember while allowing the optical access through the second clearoptical aperture and the first clear optical aperture into the chamber.17. A multi-function process chamber window assembly for protecting anaccess region for access to a process chamber from an electric fieldgenerated adjacent to the process chamber window while providing atleast two gas inlets to the process chamber and allowing optical accessto the chamber, the assembly comprising: an integrated shield and gassupply unit for protecting the access region from the electric field,the unit having a thin three-dimensional protrusion at a first end andbeing configured with a body that is thicker than the protrusion, thebody being further configured to extend from the first end parallel toan access region axis to a second end, the body being further configuredwith a first annular wall defining a unit clear aperture extending alongthe axis from the first end to the second end, the body being furtherconfigured with a first gas supply bore extending parallel to the axisand intersecting the unit clear optical aperture adjacent to the firstend, the body being further configured with a first coupler, the unitbeing fabricated from material adapted to substantially block theelectric field so that the unit clear optical aperture is protected fromthe electric field; a window member configured with respect to theaccess region axis, the member being configured with outer and chambersides and a groove extending from the outer side into the member, thegroove extending parallel to the axis, the groove being configured toreceive the thin protrusion to protect a first section of the accessregion from the electric field, the member being further configured witha second coupler configured to cooperate with the first coupler to holdthe protrusion in the groove with the unit extending away from the outerside of the member so that a second section of the access region isdefined by and is protected by the body from the electric field, thewindow member being further configured with a window member clearoptical aperture having a second annular wall extending co-axially withthe axis and configured with an axial length between the outer side andthe chamber side, the window member clear optical aperture being partlysurrounded by the thin protrusion received in the groove, the windowmember clear optical aperture being further configured with a diameter;and a coating on the second annular wall, the second annular wall withthe coating having an inner coating diameter that is substantially thesame as a value of the axial length of the window member clear opticalaperture, the coating protecting the window member clear opticalaperture from the electric field, the material from which the coating isfabricated being taken from the group consisting of cerium oxide,zirconium oxide, yttria-stabilized zirconia, thermally-sprayed aluminumoxide, yttrium oxide, and yttrium oxide having pores, wherein the poresare sealed with a material taken from the group consisting ofmethacylate ester and polymer.
 18. An assembly as recited in claim 17,wherein: the body of the unit is further configured with a second gassupply bore extending parallel to the axis and to the first end; and thewindow member is further configured with a plenum extending from theouter side into the member, plenum receiving gas from the second gassupply bore, the window member being configured with a plurality ofnozzles that are spaced around the axis and receive the gas from theplenum.
 19. An assembly as recited in claim 17, wherein: the body of theunit is further configured with a pair of co-axial annular recesses, afirst of the recesses is between the unit clear optical aperture and thesecond gas supply bore, a second of the recesses is between the secondgas supply bore and the annular groove; the assembly further comprises aseal member received in each of the recesses in opposition to the outerside of the window member; and with the couplers holding the protrusionin the groove the outer side of the window member is held opposed to theseal members in the recesses to seal the second gas supply bore to theplenum and seal the unit clear optical aperture to the window memberclear optical aperture while allowing optical access through the unitclear optical aperture and the window member clear optical aperture intothe chamber.
 20. An assembly as recited in claim 17, wherein: the secondend of the body of the integrated unit is further configured with aseat; the assembly further comprises an optical window configured forreception in the seat and a clamp for holding the optical window in theseat; and the second end is spaced from the first end to locate the seatfor the optical window where a strength of the electric field issubstantially reduced as compared to an electric field strength adjacentto the process chamber window.